import java.util.ArrayList;
import java.util.List;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: xiaotutu
 * Date: 2024-04-10
 * Time: 16:36
 */

class Solution {
    public static List<List<Integer>> generate(int numRows) {
        List<List<Integer>> ret = new ArrayList<>();
        List<Integer> list = new ArrayList<>();
        list.add(1);
        ret.add(list);

        for (int i = 1; i < numRows; i++) {
            List<Integer> curRow = new ArrayList<>();
            curRow.add(1);
            for (int j = 1; j < i; j++) {
                List<Integer> preRow = ret.get(i-1);
                int val = preRow.get(j) + preRow.get(j-1);
                curRow.add(val);
            }
            curRow.add(1);
            ret.add(curRow);
        }
        return ret;
    }

    public static void main(String[] args) {
        List<List<Integer>> ret = generate(5);
        System.out.println(ret);
    }
}
public class Test2 {
    public static void main(String[] args) {

    }
}
